The aim of this study was to characterize the neurochemical abnormalities related to N-acetyl-aspartate which is a neuronal marker, within an epilepticus focus located in the internal-temporal area, using proton magnetic resonance spectroscopy. Eleven patients with a mono-hippocampal epileptics focus on clinical and per-critical electroencephalographical criteria, were matched with 11 controls by age, sex and laterality. Proton spectroscopy of a volume of 8 cm3 was performed within the ipsilateral and the contralateral internal-temporal area and within the 2 hippocampus of controls. Volumetry of the ipsilateral and the contralateral hippocampus and of the 2 hippocampus of controls was performed using resonance magnetic imaging. All these measurements were performed during the interictal stage. The results were concordant to show a decrease of the ratio N-acetyl-aspartate/choline and N-acetyl-aspartate/creatine within the epilepticus focus, in relation with a hippocampal atrophy. This study finds similar results to those of other previous works. The decrease of N-acetyl-aspartate levels within the epilepticus focus could be related to a decrease of the neuronal cell density. This procedure is able to show a decrease of the levels of this metabolite within an internal temporal epilepticus focus and associated with a hippocampal atrophy.